Technical Yearbook 2023

MARCH

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Bentonite and laccase – a doomed attraction By Bernard Mocke

If you think that laccase can be removed from juice by bentonite, then the (rotten) joke’s on you. This stubborn rumour needs to be squashed right now. Rather consider using specific oenological tannins to address laccase. An oxidative wrecking ball called laccase The presence of laccase in grapes infected by Botrytis cinerea is well-documented and certainly nothing to be too cavalier about. The highly oxidative laccase, an enzyme (and thus also a protein) which is quite stable in juice and wine, can cause serious oxidative damage and needs to be

bounced from your juice as soon as possible. Unless you like browning and premature ageing in your wine, of course. While maintaining an anaerobic environment to curb laccase activity in affected juice is a widely adopted technique by now, unfortunately there are also still some who believe that bentonite will remove laccase from juice. This is not true. At typical juice pH, both laccase and bentonite are charged negatively, which means according to the laws of physical attraction, there simply is no attraction. Otherwise put, bentonite will not remove laccase. Only at a pH of 2.9 and lower will bentonite bind to laccase and thus reduce its activity. Let the real bouncers do their job If you’re looking for a burly fellow with busted-up knuckles

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TECHNICAL YEARBOOK 2023